Cortex-A8 R2P2.pdf - ARM Information Center

Unaligned Data and Mixed-endian Data SupportNormal memoryNormal memory conforms to the following rules concerning NEON alignmentqualifiers:• If an alignment qualifier is specified, a check is made for strict alignment basedon the qualifier, independent of the A-bit setting. Table 4-1 shows the NEONalignment qualifiers:Table 4-1 NEON normal memory alignment qualifiersAlignment specifierLow-order address bits@16 Address[0] = b0@32 Address[1:0] = b00@64 Address[2:0] = b000@128 Address[3:0] = b0000• If an alignment qualifier is not specified, and A=1, the alignment fault is taken ifit is not aligned to element size.• If an alignment qualifier is not specified, and A=0, it is treated as unalignedaccess.Device memory and strongly ordered memoryStrongly ordered or device memory conforms to the following rules concerning NEONalignment qualifiers:• if an alignment qualifier is specified, a check is made for strict alignment basedon the qualifier, independent of the A-bit setting as Table 4-1 shows• independent of the A bit, the alignment fault is taken if it is not aligned to elementsize• access to the external memory is handled by creating a burst sequence of elementsized transfers, up to the bus width.4-4 Copyright © 2006-2008 ARM Limited. All rights reserved. ARM DDI 0344E